Hello

i have issue with button, i want add "Close the survey window" button on the last page on the survey (Completed page) is that possible?

It depends on the browser - most browser don't allow this or at least ask the user for confirmation. Some allow that you can only reliably close a window by Javascript that was previously opened by JavaScript.

So its possible, but you don't recommending it ?

I am not recommending it.

Besides not recommending it, but I personally don't see the advantage of it. Users of a browser usually know how to close a window (depending on ther Operating system), so you would add a function that the browser itself already offers, is easily accesible and most users will know how to use it.